Ankit works twice as fast as Anju. Anju works twice as fast as Chandan. Ankit works 16 times as his efficiency and complete the whole in 12 days, how many days would be required for Anju if she works 32 times of her efficiency, and Chandan with 64 times of his efficiency together to complete the same job?

Let Chandan's normal efficiency be 1 unit/day. Then Anju's normal efficiency is 2 units/day, and Ankit's normal efficiency is 4 units/day. Ankit at 16x efficiency works at 64 units/day and completes the job in 12 days, so total work = 64 x 12 = 768 units. Anju at 32x efficiency = 64 units/day. Chandan at 64x efficiency = 64 units/day. Together they work at 128 units/day. Time = 768 / 128 = 6 days.